The idea of mercy killing or euthanasia was introduced in the 1930's when Hitler wanted to get rid of many people with disorders-mentally and physically. The way to get rid of the children was to mark them with either (+) (-) or (+++). The red + meant the decision was to kill the child. A blue - was a decision against killing. Three plus symbols meant the child had a euthanasia warrant and was to be transferred to a 'Children's Specialty Department'. Here, they either had death by injection or gradual starvation.